Newswise — A doctoral student in the kinesiology department at the University of Massachusetts Amherst has begun an in-depth study of a foot disorder that affects more than 2 million Americans. Ryan Chang's research on the biomechanics of foot muscles and connective tissue will help scientists to understand the mechanisms that cause chronic heel pain and may lead to more specialized treatment of the disorder.
Chang's preliminary results give the first experimental evidence to confirm the theory behind the disorder plantar fasciitis, or chronic heel pain. People with the disorder have more flexible arches than those that do not, and the front and back portions of affected feet often move out of sync. Chang's current research will take these results a step further and use magnetic resonance imaging (MRI) and spectroscopy (MRS) to determine the causes of these differences in foot mechanics.
Chang is one of only two graduate students invited to present their results at the Prescription Foot Orthotics Laboratory Association's annual biomechanics conference Nov. 16-18; the conference traditionally invites Ph.D. scientists and established podiatrists to speak. The research is a collaboration between the biomechanics laboratory, led by Joseph Hamill, and the muscle physiology laboratory, led by Jane Kent-Braun, in the department of kinesiology. The MRI's will be performed at Cooley Dickinson Hospital and the MRS work is a collaboration with Yale University.
Chronic heel pain most often affects people whose jobs require them to work on their feet, such as service workers, hospital workers, flight attendants, postal workers and construction workers, said Chang. Many people affected by the disorder describe the symptoms as a sharp, knife-like pain in their heel. The disorder gets its name from the portion of the foot that it is believed to affect: the plantar fascia, which is a strip of connective tissue that attaches to the bottom of the heel and runs along the arch of the foot, fanning out to attach to all five toes. Clinicians have traditionally associated the painful symptoms with over-stretching and inflammation of the connective tissue, but this correlation has never been proven. "One of the biggest problems is that there's no good way to diagnose this disorder based on people in a static position," said Hamill. "If you're standing, you're not going to see a problem that's a result of motion. You have to watch a person walking to understand why they have that pain."
The first part of Chang's study compares the way affected people walk with those who are not affected. In the biomechanics laboratory, Chang places 11 pieces of reflective tape on various parts of the foot, ankle and calf of his subjects. He then films each subject walking along a walkway using several infrared cameras; the video is then used to reconstruct the subject's movements in three dimensions. The subjects also walk over a force platform that records the levels of force that are exerted by different parts of the foot. Chang's initial results suggest that plantar fasciitis patients have more flexible arches that are more easily flattened while walking. Further, the front and rear portions of affected people's feet do not bend in sync with each other the way a normal person's foot moves. "We're finding that there's more to foot problems than just the way the foot flexes," said Chang. "We're characterizing finer-scale movement patterns and the ways the angles of movement change when you use your foot." As a certified pedorthist, Chang designs and manufactures braces that help support the foot and correct its function. He hopes his results will improve current treatments for the disorder, which include stretching, muscle strengthening, icing and wearing specialized footwear and arch supports. The second and third parts of Chang's project will uncover the mechanisms behind these flexibility and movement issues in plantar fasciitis patients. Using MRI and MRS, Chang's group will be able to compare the size and shape of the foot's individual muscles with the amount of energy the muscles produce when a subject walks. Kent-Braun, who specializes in the mechanisms of muscle fatigue, thinks Chang's results will be especially informative to studies on how people's muscles change with age. "Thus far we've had no information about the mechanisms of this disorder," Kent-Braun said. "The structure and the way it functions are so complex, and it's only recently that we've begun to have the tools to examine it."
The scientists are seeking otherwise healthy, non-obese people between the ages of 30 and 55 for participation in this study. If you fit the above criteria and have been diagnosed with plantar fasciitis or have experienced its symptoms, call 413/545-4421 or e-mail Ryan Chang at [email protected] for further information. Qualified subjects will receive a free custom set of foot orthotics.
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